Messages in this thread | | | Date | Thu, 18 Mar 2021 17:58:38 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/3] static_call: Fix static_call_update() sanity check |
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On Thu, Mar 18, 2021 at 11:13:08AM -0500, Josh Poimboeuf wrote: > On Thu, Mar 18, 2021 at 12:31:59PM +0100, Peter Zijlstra wrote: > > if (!kernel_text_address((unsigned long)site_addr)) { > > - WARN_ONCE(1, "can't patch static call site at %pS", > > + /* > > + * This skips patching __exit, which is part of
This skips patching built-in __exit, ... ?
> > + * init_section_contains() but is not part of > > + * kernel_text_address(). > > + * > > + * Skipping __exit is fine since it will never
+ built-in, again
> > + * be executed. > > + */ > > + WARN_ONCE(!static_call_is_init(site), > > + "can't patch static call site at %pS", > > site_addr); > > continue; > > } > > It might be good to clarify the situation for __exit in modules in the > comment and/or changelog, as they both seem to be implicitly talking > only about __exit in vmlinux.
Correct.
> For CONFIG_MODULE_UNLOAD, the code ends up in the normal text area, so > static_call_is_init() is false and kernel_text_address() is true. > > For !CONFIG_MODULE_UNLOAD, the code gets discarded during module load, > so static_call_is_init() and kernel_text_address() are both false. I > guess that will trigger a warning?
Oh gawd, more variants.
Afaict MODULE_UNLOAD, by virtue of that #ifdef in rewrite_section_headers() won't even load the .exit sections. Afaict that will break: alterative, jump_label and static_call patching all in one go.
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